Such devices are used in a vehicle drive train to transmit drive torque and drive power from an electric drive motor and, if necessary, a second drive motor to components of the vehicle drive train such as a main gearing or distributor gearing. For this purpose, the second drive motor can be mechanically coupled to the device in the sense of a parallel hybrid drive train and, together with the electric drive motor, drive the components of the drive train, or, in the sense of a serial hybrid drive train, the second drive motor can be connected to a generator which is electrically connected to the electric drive motor which drives the components of the drive train on its own. According to both variants of the drive train, the electric drive motor is typically connected to a rechargeable energy accumulator and is operated, as needed, either as a generator to charge the energy accumulator or as a motor to drive the components of the drive train and thereby discharge the energy accumulator.
FIG. 1 in DE 100 33 424 A1 and the description therein disclose a device for a vehicle drive train for generating and transmitting drive torque to components of the drive train comprising a shaft, which is a transmission input shaft in this case, the input side of which can be operatively connected via a clutch to a drive motor, and the output side of which is operatively connected to further components of the drive train i.e. a transmission in this case. The device also comprises one first and one second bearing which rotatably support the shaft in a housing, and an electric drive motor which is disposed between the first and the second bearing and is composed of a stationary stator and a rotor which is non-rotatably coupled to the shaft. The rotor is non-rotatably coupled to the shaft via a gearwheel profile of the shaft on which the rotor lies via a plurality of bearing surfaces.
In such a device, transmission of drive torque from the shaft to the components of the drive train can cause transverse forces that act perpendicularly to the longitudinal direction of the shaft to be introduced into the shaft, e.g. when the shaft is coupled via a gear to a countershaft of a transmission and the electric drive motor introduces drive torque into the shaft during operation. These transverse forces, the intensity of which depends e.g. on the transmitted drive torque and the interconnection of the transmission, cause the shaft to bend, thereby changing the orientation of the rotor relative to the stator in terms of position and angle. The tilt of the rotor, in particular relative to the stator due to the deflection angle in the region of the bearing surface of the rotor, negatively affects the performance of the electric drive motor since the electric fields generated during operation of the electric drive motor no longer enter the rotor and the stator constantly at an intended favorable angle. Moreover, if the longitudinal dimension of the rotor is long, the tilting can cause the rotor to collide with the stator and thereby destroy the electric drive motor.